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Fig. 7 Composite Hog Chilling Time/TemperatureCurves

Fig. 7 Composite Hog Chilling Time/TemperatureCurves

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30.10
air distribution pattern requires careful attention to prevent drafts on
the workers.
Forced-air units are satisfactory for refrigerating cutting floors.
Ceiling height must be sufficient to accommodate the units. A
wide selection of forced-air units may be applied to these rooms.
They can be floor or ceiling mounted, with either dry-coil or
wetted-surface units arranged for flooded, recirculated, or directexpansion refrigerant systems.
Suction pressure regulators should be provided for both flooded
and direct-expansion units. Automatic dry- and wet-bulb controls are
essential for best operation.

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Pork Trimmings
Pork trimmings come from the chilled hog carcass, principally
from the primal cuts: belly, plate, back fat, shoulder, and ham.
Trimmings per hog average 1.8 to 3.6 kg. Only trimmings used in
sausage or canning operations are discussed here.
In the cutting or trimming room, trimmings are usually between 3 to 7°C; an engineer must design for the higher temperature. The product requires only moderate chilling to be in proper
condition for grinding, if it is to be used locally in sausage or canning operations. If it is to be stored or shipped elsewhere, hard
chilling is required. Satisfactory final temperature for local processing is –2°C. This is the average temperature after tempering
and should not be confused with surface temperature immediately
after chilling. Trimmings may be much cooler on the surface than
on the interior immediately after chilling, especially if they have
been quick-chilled.
Good operating practice requires rapid chilling of pork trimmings as soon as possible after removal from the primal cuts. This
retards enzymatic action and microbial growth, which are responsible for poor flavor, rancidity, loss of color, and excessive shrinkage.
The choice of chilling method depends largely on local conditions and consists of a variation of air temperature, air velocity, and
method of achieving contact between air and meat. Continuous belt
equipment using low-temperature air or fluids to obtain lower
shrinkage is available.
Truck Chilling. Economic conditions may require existing
chilling or freezer rooms to be used. Some may require an overnight
chill, others less than an hour. The following methods make use of
existing facilities:
• Trimmings are often chilled with CO2 snow before grinding to
prevent excessive temperature rise during grinding and blending.
Additionally, finished products, such as sausage or hamburger in
chubs, may be crusted or frozen in a glycol/brine liquid contact
chiller.
• Trimmings are put on truck pans to a depth of 50 to 100 mm and held
in a suitable cooler kept at –1°C. This method requires a short chill
time and results in a near-uniform temperature (–1°C) of trimmings.
• Trimmings are spread 100 to 125 mm deep on truck pans in a
–20°C freezer and held for 5 to 6 h, or until the meat is well stiffened with frost. Using temperatures below –20°C (with or without
fans) expedites chilling if time is limited. After trimmings are
hard-chilled, they are removed from the metal pans and tightly
packed into suitable containers. They are held in a –3 to –2°C
room until shipped or used. Average shrinkage using this system
is 0.5% up to the time they are put in the containers.
• Trimmings from the cutting or trimming room are put in a meat
truck and held in a cooler at –2 to –1°C. This method usually
requires an overnight chill and is not likely to reach a temperature
of 0°C in the center of the load.
• If trimmings are not to be used within one week, they should be
frozen immediately and held at –23°C or lower.

2010 ASHRAE Handbook—Refrigeration (SI)
Forced-air cooling units are frequently used for holding room
service because they provide better air circulation and more uniform
temperatures throughout the room, minimize ceiling condensation
caused by air entering doorways from adjacent warmer areas
(because of traffic), and eliminate the necessity of coil scraping or
drip troughs if hot-gas defrost is used.
Cooling units may be the dry type with hot-gas defrost, or wetted
surface with brine spray. Units should have air diffusers to prevent
direct air blast on the products. Unless the room shape is very odd,
discharge ductwork should not be necessary.
Because the product is boxed and wrapped and the holding
period is short, humidity control is not too important. Various methods of automatic control may be used. CO2 has been used in boxes
of pork cuts. Care must be taken to maintain the ratio of kilograms
of CO2 to kilograms of meat for the retention period. The enclosures
must be relieved and ventilated in the interest of life safety.

Calf and Lamb Chilling
Dry coils (either the between-the-rail type, the suspended type
above the rail, or floor units) are typically used for calf and lamb
chilling. The same type of refrigerating units used for pork may be
used for lamb, with some modifications. For example, in chilling
lambs and calves, it is desirable to reduce air changes over the carcass by using two-speed motors, using the higher speed for the
initial chill and reducing the rate of air circulation when carcass
temperatures are reduced, approximately 4 to 6 h after the cooler is
loaded.
Lambs usually have a mass of 18 to 36 kg, with an approximate
average dressed carcass mass of 23 kg. Sheep have a mass up to an
average of approximately 57 kg and readily take refrigeration. Adequate coil surface should be installed to maintain a room temperature below –1°C and 90 to 95% rh in the loading period. The
evaporating capacity should be based on an average 5 K temperature
differential between refrigerant and room air temperature, with an
opening room temperature of 0°C.
Compensating back-pressure-regulating valves, which vary the
evaporator pressure as room temperature changes, should be used.
As room and carcass temperatures drop, the temperature differential
is reduced, thus holding a high relative humidity (40 to 45%). At the
end of a 4 to 6 h chill period, air over the carcass may be reduced to
help keep product bloom and color.
Carcasses should not touch each other. They enter the cooler at 37
to 39°C, with the carcass temperature taken at the center of the heavy
section of the rear leg. The specific heat of a carcass is 2.9 kJ/(kg·K).
Air circulation for the first 4 to 6 h should be approximately 50 to 60
changes per hour, reduced to 10 to 12 changes per hour. The carcass
should reach 1 to 2°C internally in about 12 to 14 h and should be
held at that point with 85 to 90% rh room air until shipped or otherwise processed. This gives the least possible shrinkage and prevents
excess surface moisture.
In calf-chilling coolers, approximately the same procedure is
acceptable, with carcasses hung on 300 to 380 mm centers. The
dressed mass varies at different locations, with an approximate 39 to
41 kg average in dairy country and a 90 to 160 kg (sometimes
heavier) average in beef-producing localities. The same time and
temperature relationship and air velocities for chilling lambs are
used for chilling calves, except when calves are chilled with the hide
on. Also, the time may be extended for air circulation. Air circulation need not be curtailed in hide-on chilling because rapid cooling
gives better color to these carcasses after they are skinned.
Refrigerating capacity for lamb- and calf-chill coolers is calculated the same as for other coolers, but additional capacity should be
added to allow reduced air circulation and maintain close temperature differential between room air and refrigerant.

Fresh Pork Holding
Fresh pork cuts are usually packed on the cutting floor. If they are
not shipped the same day that they are cut and packed, they should
be held in a cooler with a temperature of –7 to –2°C.

Chilling and Freezing Variety Meats
The temperature of variety meats must be lowered rapidly to –2
to –1°C to reduce spoilage. Large boxes are particularly difficult to

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30.11

cool. For example, a 125 mm deep box containing 32 kg of hot variety meat can still have a core temperature as high as 16°C 24 h after
it enters a –30°C freezer. Variety meats in boxes or packages more
than 75 mm thick may be chilled very effectively during freezing by
adding dry ice to the center of the box.
For design calculations, variety meat has an initial temperature
of about 38°C. Specific heats of variety meats vary with the percentage of fat and moisture in each. For design purposes, a specific heat
of 3.1 kJ/(kg·K) should be used.
Quick Chilling. A better and more widely used method consists
of quick chilling at lower temperatures and higher air velocities,
using the same type of truck equipment as in the overnight chilling
method. This method is also used for chilling trimmings. Careful
design of the quick-chilling cabinet or room is needed to provide for
the refrigeration load imposed by the hot product. One industry survey shows that approximately 50% of large establishments use
quick-chill in their variety meat operations.
The quick-chilling cabinet or room should be designed to operate
at an air temperature of approximately –30 to –40°C, with air velocities over the product of 2.5 to 5 m/s. During initial loading, the air
temperature may rise to –20°C. In quick-chilling unit design, refrigeration coils are used with axial-flow fans for air circulation.
The recommended defrosting method is with water and/or hot
gas, except where units with continuous defrost are used. The product is chilled to the point where the outside is frosted or frozen and
a temperature of –2 to –1°C is obtained when the product later
reaches an even temperature throughout in the packing or tempering
room. The time required to chill the product by this method depends
on the depth of product in the pans, size of individual pieces, air
temperature, and velocity. Normally, 0.5 to 4 h is a satisfactory chill
period to attain the required –2 to –1°C temperature. In addition to
the obvious savings in time and space, an important advantage of
this method is the low total shrinkage, averaging only 0.5 to 1%.
These values were obtained in the same survey as those in Table 7.
Packaging Before Chilling. Another method of handling variety
meats involves packaging the product before chilling, as near as
possible to the killing floor. Packed containers are placed on platforms and frozen in a freezer. Separators should allow air circulation
between packages.
This method is used in preparing products for frozen shipment or
freezer storage. The internal temperature of the product should
reach –4°C for prompt transfer to a storage freezer. For immediate
shipment, the internal temperature of the product must be reduced to
–20°C; this may be done by longer retention in the quick freezer.
Here package material and size, particularly package thickness,
largely determine the rate of freezing. For example, a 125 mm thick
box takes at least 16 h to freeze, depending on the type of product,
package material, size, and loading method.
The dry-bulb air temperature in these freezers is kept at –40 to
–30°C, with air velocities over the product at 2.5 to 5 m/s. The
Table 7 Storage Life of Meat Products
Months
Temperature, °C
Product
Beef
Lamb
Veal
Pork
Chopped beef
Pork sausage
Smoked ham and bacon
Uncured ham and bacon
Beef liver
Cooked foods

–12

–18

–23

–29

4 to 12
3 to 8
3 to 4
2 to 6
3 to 4
1 to 2
1 to 3
2
2 to 3
2 to 3

6 to 18
6 to 16
4 to 14
4 to 12
4 to 6
2 to 6
2 to 4
4
2 to 4
2 to 4

12 to 24
12 to 18
8
8 to 15
8
3
3
6

12+
12+
12
10
10
4
4
6

time required to reach the desired internal temperature depends on
refrigeration capacity, size of largest package, insulating properties of package material, and so forth. A generous safety factor
should be used in sizing evaporator coils. These freezers are best
incorporated in refrigerated rooms. Defrosting is by water or hot
gas, except where units with continuous defrost are used. Shrinkage varies in the range of only 0.5 to 1%.
Initial freezing equipment cost and design load can be reduced if
carbon dioxide is included in packaging as part of the operational
plan. Another efficient cooling method uses plate freezers to form
blocks of product that can be loaded on pallets with minimal packaging.

Packaging and Storage
Packages for variety meats do not have standard sizes or dimensions. Present requirements are a package that will stand shipping,
with sizes to suit individual establishments. The package’s importance becomes more apparent with the hot-pack freezing method.
Standardized sizes and package materials promote faster chilling
and more economical handling.
Storage of variety meats depends on its end use. For short storage
(under one week) and local use, –2 to –1°C is considered a good
internal product temperature. If stored for shipping, the internal
temperature of the product should be kept at –20°C or below. Recommended length of storage is controversial; type of package,
freezer temperature and relative humidity, amount of moisture
removed in original chill, and variations of the products themselves
all affect storage life.
Packers’ storage time recommendations vary from 2 to 6 months
and longer, because variety meats pick up rancidity on the surface
and soft muscle tissue dehydrates while freezing. More rapid freezing and vaporproof packaging are important in increasing storage
life.

Packaged Fresh Cuts
In packaging fresh cuts of meat intended for direct placement
into retail display cases, sanitation of the processing room is particularly important. The same environmental concerns also apply to
some processors of precooked, ready-to-eat products.
Uncooked fresh cuts are packaged in sealed packages with an
atmosphere of sterile nitrogen/oxygen/carbon dioxide mixture to
control pathogens and organic activity. Shelf life is extended from
days to weeks.
It is important to prepare and package this product in an environment free of harmful bacteria and other pathogens, and to transport
these products at a continuously controlled temperature to the market display case. Techniques to accomplish this include
• Processing room temperature of 2 to 3°C
• A semi-cleanroom environment with positive air pressure created
by highly filtered, refrigerated outdoor air
• Keeping only packaging film and pouches in the room (e.g., no
boxes or cardboard)
• A program of follow-through with temperature-monitoring devices shipped with the product, and returned
Cleanroom techniques include an isolated workcrew entering
through a sanitation anteroom, changing outer garments, wearing
hair nets, using footbath sanitation, and handwashing with disinfection. Facilities for frequent microbiological testing should be
provided.

Refrigeration Load Computations
The average evaporator refrigerating load for a typical chilling
process above freezing may be computed as follows:

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30.12

2010 ASHRAE Handbook—Refrigeration (SI)
qr = mm cm(t1 – t2) + mt ct (t1 – t2) + qw + qi + qm

(1)

Table 8

where
qr
mm
mt
cm
ct

=
=
=
=
=

t1
t2
qw
qi
qm

=
=
=
=
=

refrigeration load, kW
mass of meat, kg/s
mass of trucks, kg/s
specific heat of meat, kJ/(kg·K)
specific heat of truck, containers, or platforms
(0. 0.50 for steel), kJ/(kg·K)
average initial temperature, °C
average final temperature, °C
heat gain through room surfaces, kW
heat gain from infiltration, kW
heat gain from equipment and lighting, kW

The following example illustrates the method of computing the
refrigeration load for a quick-chill operation.

Licensed for single user. © 2010 ASHRAE, Inc.

Example 2. Find the refrigeration load for chilling six trucks of offal
from a maximum temperature of 38 to 1°C in 2 h. Each truck has a
mass of 180 kg empty and holds 330 kg of offal. The specific heat is
0.50 kJ/(kg ·K) for the truck and 3.14 kJ/(kg ·K) for the offal. The
room temperature is to be held at –18°C, with an outdoor temperature
of 4°C and 70% rh. The walls, ceiling, and floor gain 0.426 W/(m2 ·K)
and have an area of 88 m2. The room volume is 53 m3 and 12 air
changes in 24 h are assumed.
Solution: Values for substitution in Equation (1) are as follows:
mm
cm
mt
ct
qw

=
=
=
=
=

6 × 330/2 = 990 kg/h = 0.275 kg/s
3.14 kJ/(kg·K)
6 × 180/2 = 540 kg/h = 0.15 kg/s
0.50 kJ/(kg·K)
88 × 0.426 [4 – (–18)] = 0.82 kW

From a psychrometric chart or table, the heat removed from the infiltrating air is 41.6 kJ/m3. Then,
qi
qm
7.5
0.2

=
=
=
=

41.6 × 53 × 12/(24 × 3600) = 0.31 kW
7.5 + 0.2 = 7.7 kW, where
assumed fan and motor kilowatts
lights in kilowatts

Substituting in Equation (1),
qr = 0.275  3.14(38 – 1) + 0.15  0.50(38 – 1)
+ 0.82 + 0.31 + 7.7 = 43.6 kW
Good practice is to add 10 to 25% to the computed refrigeration load.

PROCESSED MEATS
Prompt chilling, handling, and storage under controlled temperatures help in production of mild and rapidly cured and smoked
meats. The product is usually transferred directly from the smokehouse to a refrigerated room, but sometimes a drop of 5 to 15 K can
occur if the transfer time is appreciable.
Because the day’s production is not usually removed from the
smokehouses at one time, the refrigeration load is spread over
nearly 24 h. Table 8 outlines temperatures, relative humidities, and
time required in refrigerated rooms used in handling smoked meats.
Prechilling smoked meat reduces drips of moisture and fat, thus
increasing yield. Meats can be chilled at higher temperatures, with air
velocities of up to 2.5 m/s (Table 8). At lower temperatures, air velocities of 5 m/s and higher are used. Chilling in the hanging or wrapping
and packaging rooms results in slow chilling and high temperatures
when packing. Slow chilling is not desirable for a product that is to
be stored or shipped a considerable distance.
Meats handled through smoke and into refrigerated rooms are
hung or racked on cages that are moved on an overhead track or
mounted on wheels. Sometimes the product is transferred from
suspended cages to wheel-mounted cages between smoking and
subsequent handling.
Smoked hams and picnic meats must be chilled as rapidly as possible through the incubation temperature range of 40 to 10°C. A

Room Temperatures and Relative Humidities
for Smoking Meats
Room Conditions
°C
% Relative Final Product Time,
Dry-Bulb Humidity
Temp., °C
h

Prechill method
Hams, picnics, etc.
High temperature
Low temperature
Derind bacon
Normal
Blast

3 to 4
–3 to –2

80
80

15
15

8 to 10
2 to 3

–3 to –2
–18 to –12

80
80

–2
–3

8 to 10
2 to 3

Hanging or tempering
Ham, picnics, etc.
Derind bacon

7 to 10
–3 to –2

70
70

10 to 13
–3 to –2

Wrapping or packaging
Hams, picnics, etc.

7 to 10

70

Storage

–2 to 7

70

product requiring cooking before eating is brought to a minimum
internal temperature of 60°C to destroy possible live trichinae,
whereas one not requiring cooking before eating is brought to a minimum internal temperature of 68°C.
Maximum storage room temperature should be 5°C db when
delivery from the plant to retail outlets is made within a short time.
A room dry-bulb temperature of –2 to 0°C is desirable when delivery is to points distant from the plant and transfer is made through
controlled low-humidity rooms, docks, cars, or trucks, keeping the
dew point below that of the product.
Bacon usually reaches a maximum temperature of 52°C in the
smokehouse. Because most sliced smoked bacon is packaged, it
may be transferred directly to the chill room if it has been skinned
before smoking. If bacon is to be skinned after smoking, it is usually
allowed to hang in the smokehouse vestibule for 2 to 4 h, until it
drops to 32°C before skinning.
Bacon is usually molded and sliced at temperatures just below
–2°C. Chill rooms are usually designed to reduce the bacon’s internal temperature to –3°C in 24 h or less, requiring a room dry-bulb
temperature of –8 to –7°C. A tempering room (which also serves as
storage for stock reserve), held at the exact temperature at which
bacon is sliced, is often used.
Bacon can be molded either after tempering, in which case it is
moved directly to the slicing machines, or after the initial hardening, and then be transferred to the tempering room. In the latter
case, care should be taken that none of the slabs is below –4°C so
that the product will not crack during molding. Bacon cured by the
pickle injection process generally shows fewer pickle pockets if it
is molded after hardening, placed no more than eight slabs high on
pallets, and held in the tempering room.
In any of these rooms, air distribution must be uniform. To minimize shrinkage, the air supply from floor-mounted unit coolers
should be delivered through slotted ducts or by closed ducts supplying properly spaced diffusers directed so that no high-velocity airstreams impinge on the product itself. The exception is in blast chill
rooms, which need high air velocities but subject the product to the
condition for only a short time.
Refrigeration may be supplied by floor- or ceiling-mounted dryor wet-coil units. If the latter are selected, water, hot-gas, or electric
defrost must also be used.
Many processors use three methods of chilling smoked meats:
rapid blast, direct-contact spraying of brine, and cryogenic. Directcontact spraying is especially emphasized, because it minimizes
shrinkage, increases shelf life, and provides more uniform chilling.
This method is usually carried out in special enclosures designed to

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Meat Products
combat the detrimental effects of salt brine. Color and salt taste may
need close monitoring in contact spraying.
The product should enter the slicing room chilled to a uniform
internal temperature not to exceed 10°C for beef rounds and 5 to
7°C for other fresh carcass parts, depending on the individual
packer’s temperature standard. Internal temperatures below –3°C
tend to cause shattering of products such as bacon during slicing and
slow processing. For that type of product, temperatures above 0°C
cause improper shingling from the slicing machine.
The slicing and packaging room temperature and air movement
are usually the result of a compromise between the physical comfort
demands of operating personnel and the product’s requirements.
The design room dry-bulb temperature should be below 10°C,
according to USDA-FSIS regulations.
An objectionable amount of condensation on the product may
occur. To guard against this, the coil temperature should be maintained below the temperature of bacon entering the room, thus
keeping the room air’s dew point below the product temperature.
Product should be exposed to room air for the shortest possible
time.

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Bacon Slicing and Packaging Room
Exhaust ventilation should remove smoke and fumes from the
sealing and packaging equipment and comply with OSHA occupancy regulations. Again, consider using heat exchangers to
reduce the resulting increased refrigeration load.
Refrigeration for this room may be supplied by forced-air units
(floor or ceiling mounted, dry or wet coil) or finned-tube ceiling
coils. Dry coils should have defrost facilities if coil temperatures
are to be kept at more than several degrees below freezing. Air discharge and return should be evenly distributed, using ductwork if
necessary. To avoid drafts on personnel, air velocities in the occupied zone should be in the range of 0.13 to 0.18 m/s. The temperature differential between primary air and room air should not
exceed 5 K, to ensure personnel comfort. For optimum comfort
and dew-point control, reheat coils are necessary.
Where ceiling heights are adequate, multiple ceiling units can be
used to minimize the amount of ductwork. Automatic temperature
and humidity controls are desirable in cooling units.
To provide draft-free conditions, drip troughs with suitable
drainage should be added to finned-tube ceiling coils. However, it is
difficult, if not impossible, to maintain a room air dew point low
enough to approach the product temperature. Some installations
operating with relative humidities of 60 to 70% do not have product
condensation problems.
One control method consists of individual coil banks connected
to common liquid and suction headers. Each bank is equipped with
a thermal expansion valve. The suction header has an automatically
operated back-pressure valve. The thermostatically controlled dual
back-pressure regulator and liquid-header solenoid are both controlled by a single thermostat. This arrangement provides a simple
automatic defrosting cycle.
Another system uses fin coils with glycol sprays. Humidity is
controlled by varying the concentration strength of the glycol and
the refrigerant temperature.

Sausage Dry Rooms
Refrigeration or air conditioning is integral to year-round sausage dry rooms. The purpose of these systems is to produce and
control air conditions for proper moisture removal from the sausage.
Various dry sausages are manufactured, for the most part uncooked. This sausage is generally of two distinct types: smoked
and unsmoked. Keeping qualities depend on curing ingredients,
spices, and removal of moisture from the product by drying.
FSIS regulates the minimum temperature and amount of time
that the product must be held after stuffing and before release,

30.13
depending on the method of production. The dry room temperature
should not be lower than 7°C, and the length of time product is held
in the dry room depends on the sausage’s diameter after stuffing and
preparation method used.
After stuffing, sausages are held at a temperature of 16 to 24°C
and 75 to 95% rh in the sausage greenroom to develop the cure. Sausages are suspended from sticks at the time of stuffing and may be
held on the trucks or railed cages or be transferred to racks in the
greenroom. Sausages in 90 to 100 mm diameter casings are generally spaced about 150 mm on centers on the sausage sticks. The
length of time sausages are held in the greenroom depends on the
preparation method, type and dimensions of the sausage, the operator, and the sausage maker’s judgment about proper flavor, pH, and
other characteristics.
Varieties that are not smoked are then transferred to the sausage
dry room; those that are to be smoked are transferred from the
greenroom to the smokehouse and then to the dry room.
In the dry room, approximately 30% of the moisture is removed
from the sausage, to a point at which the sausage will keep for a long
time, virtually without refrigeration. The drying period required
depends on the amount of moisture to be removed to suit trade
demand, type of sausage, and type of casing. Moisture transmission
characteristics of synthetic casings vary widely and greatly influence the rate of drying. Sausage diameter is probably the most
important factor influencing the drying rate.
Small-diameter sausages, such as pepperoni, have more surface
in proportion to the mass of material than do large-diameter sausages. Furthermore, moisture from the interior has to travel a much
shorter distance to reach the surface, where it can evaporate. Thus,
drying time for small-diameter sausages is much shorter than for
large-diameter sausages.
Typical conditions in the dry room are approximately 7 to 13°C
and 60 to 75% rh. Some sausage makers favor the lower range of
temperatures for unsmoked varieties of dry sausage and the higher
range for smoked varieties.
In processing dry sausage, moisture should only be removed
from the product at the rate at which the moisture comes to the casing surface. Any attempt to hasten drying rate results in overdrying
the sausage surface, a condition known as case hardening. This
condition is identified by a dark ring inside the casing, close to the
surface of the sausage, which precludes any further attempt to
remove moisture from the interior of the sausage. On the other
hand, if sausage is dried too slowly, excessive mold occurs on the
casing surface, usually leading to an unsatisfactory appearance.
(An exception is the Hungarian salami, which requires a high
humidity so that prolific mold growth can occur and flourish.)
As with any other cool or refrigerated space, sausage dry rooms
should be properly insulated to prevent temperatures in adjoining
spaces from influencing the temperature in the room. Ample insulation is especially important for dry rooms located adjacent to
rooms of much lower temperature or rooms on the top floor, where
the ceiling may be exposed to relatively high temperatures in summer and low temperatures in winter.
Insulation should be adequate to prevent inner surfaces of the
walls, floor, and ceiling of the dry room from differing more than a
degree or two from the average temperature in the room. Otherwise, condensation is possible because of the high relative humidity in these rooms, which leads to mold growth on the surfaces
themselves and, in some cases, on the sausages as well.
Sticks of sausage are generally supported on permanent racks
built into the dry room. In the past, these were frequently made of
wood; however, sanitary requirements have virtually outlawed the
use of wood for this purpose in new construction. The uprights and
rails for the racks are now made of either galvanized pipe, hot-dip
galvanized steel, or stainless steel. Rails for supporting sausage
sticks should be spaced vertically at a distance that leaves ample
room for air circulation below the bottom row and between the top

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30.14
row and the ceiling. Spacing between rails (usually not less than
300 to 600 mm) depends on the length of sausage stick used by the
individual manufacturer.
Horizontal spacing between sausages should be such that they do
not touch at any point, to prevent mold formation or improper development of color. Generally, with large 100 mm diameter sausages,
spacing of 150 mm on centers is adequate.
Dry-Room Equipment. In general, two types of refrigeration
equipment are used to attain the required conditions in a dry room.
The most common is a refrigeration-reheat system, in which room
air is circulated either through a brine spray or over a refrigerated
coil and sufficiently cooled to reduce the dew point to the temperature required in the room. The other type involves spraying a hygroscopic liquid over a refrigerating coil in the dehumidifier, thus
condensing moisture from the air without the severe overcooling
usually required by refrigeration-reheat systems. The chief advantage of this arrangement is that refrigeration and heating loads are
greatly reduced.
Use of any type of liquid, brine or hygroscopic, requires periodic
tests and adjusting the pH to minimize equipment corrosion.
Although most systems depend on a type of liquid spray to prevent
frost build-up on the refrigerating coils, some successful rooms use
dry coils with hot-gas or water defrost.
Air for conditioning the dry room is normally drawn through the
refrigerating and dehumidifying systems by a suitable blower fan
(or fans) and discharged into the distribution ductwork.
Rooms used exclusively for small-diameter products with a rapid
drying rate may actually have air leaving the room to return to the
conditioning unit at a lower dry-bulb temperature and greater density
than at which it is introduced. A dry-room designer needs to know
what the room will be used for to determine the natural circulation of
the room air. Supply and return ducts can then be arranged to take
advantage of and accelerate this natural circulation to provide thorough mixing of incoming dry air with air in the room.
Regardless of the location of supply and return ducts, care should
be taken to prevent strong drafts or high-velocity airstreams from
impinging on the product, which leads to local overdrying and
unsatisfactory products.
Study of air circulation within the product racks shows that, as air
passes over the sausages and moisture evaporates from them, this air
becomes cooler and heavier, and thus tends to drop toward the bottom of the room, creating a vertical downward air movement in the
sausage racks. This natural tendency must be considered in designing duct installation if uniform conditions are to be achieved.
An example of the calculation involved in designing a sausage
dry room follows. These calculations apply to a room used for
assorted sausages, with an average drying time of approximately 30
days. They would not be directly applicable to a room used primarily for very large salami (which has a much longer drying period) or
small-diameter sausage.
In the latter case, using the air-circulating rate shown in this example allows the air to absorb so much moisture in passing through
the room that it is difficult to obtain uniform conditions throughout
the space. Furthermore, the amount of refrigeration required to
lower the air temperature enough to produce the required low inletair dew point becomes excessive. An air circulation rate of 12 air
changes per hour should therefore be considered average for use in
average rooms. The actual circulating rate should be adjusted to obtain the best compromise of refrigeration load and air uniformity for
the particular type of product handled.
Example 3. Air conditioning for sausage drying room
Room Dimensions:
12.2 ×10.2 × 3.5 m
Floor space: 124.4 m2
Volume: 435.5 m3
Outdoor wall area: 91 m2
Partition wall area: 71.5 m2

2010 ASHRAE Handbook—Refrigeration (SI)
Hanging Capacity:
Number of racks: 12
Length of racks: 8.25 m
Number of rails high: 5
Spacing of sticks: 0.15 m
Number of pieces of sausage per stick: 7
Average mass per sausage: 1.8 kg
Total mass: 1.8 × 12 × 5 × 7(8.25/0.15) = 41 580 kg
Assume 42 000 kg green hanging capacity
Loading per day: 700 kg
Assumed Outdoor Conditions (Summer):
35°C db; 24°C wb, h = 72 kJ/kg, W = 14.35 g/kg
Dry-Room Conditions Desired:
13°C db; 10°C wb, h = 29 kJ/kg, W = 6.4 g/kg
Sensible Heat Calculations:
Walls [U = 0.57 W/(m2 ·K)]:
0.57 × 91(35 – 13)/1000
=
1.14 kW
Partition [U = 0.38 W/(m2 ·K)]:
0.38 × 71.5(35 – 13)/1000
=
0.60 kW
Floor and ceiling [U = 0.57 W/(m2 ·K)]:
0.57 × 124.4 × 2(13 – 13)/1000
=
none
Infiltration [Assume cp = 1.20 kJ/(m3 ·K) and
0.5 air changes/h]
1.20(435.5 × 0.5/3600)(35 – 13)
=
1.60 kW
Lights
=
0.60 kW
Motors
=
3.75 kW
Daily product load
3.35[700/(24  3600)](35 – 13)
=
0.60 kW
Total sensible heat gain
=
8.29 kW
Latent Heat Calculations:
Product
700/(24  3600)  0.30  2470 kJ/kg
6.00/2470
Infiltration
1.2 435.5(0.5/3600)(72 – 29)
(3.12 – 1.60)/2470
Total moisture = 0.00243 + 0.00062

=
6.00 kW
= 0.00243 kg/s
=
3.12 kW
= 0.00062 kg/s
= 0.00305 kg/s

Assume 12 air changes per hour, with an empty room volume of
435.5 m3 or 1.2 kg/m3  435.5  12/3600 = 1.74 kg/s. Then each kilogram of air must absorb 0.00305/1.74 = 0.00175 kg of moisture.
Because air at the desired room condition contains 0.0064 kg/kg, entering air must contain 0.0064 – 0.00175 = 0.00465 kg/kg, corresponding
to about 5.0°C db and 4.0°C wb (h = 16.6 kJ/kg).
Temperature rise from sensible heat gain [air specific heat = 1.0 kJ/
(kg·K)]:
8.29/(1.75  1.0) = 4.7 K
Temperature drop caused by evaporative cooling from latent heat of
product only:
6.00/(1.74  1.0) = 3.4 K
Net temperature rise in the room = 4.7 – 3.4 = 1.3 K, or air entering the
room must be 13 – 1.6 = 11.4°C db and 7.4°C wb (0.00465 kg/kg).
Refrigerating load = 1.74(29 – 16.6) = 21.6 kW
Reheat load = 1.74(23.5 – 16.6) = 12.0 kW
Room load = 1.74(29 – 23.5) = 9.6 kW

Lard Chilling
In federally inspected plants, the USDA-FSIS designates the
types of pork fats that, when rendered, are classified as lard. Other
pork fats, when rendered, are designated as rendered pork fats. The
following data for refrigeration requirements may be used for either
product type. Rendering requires considerable heat, and the subsequent temperature of the lard at which refrigeration is to be applied
may be as high as 50°C.
The fundamental requirement of the FSIS is good sanitation
through all phases of handling. Avoid using copper or copperbearing alloys that come in contact with lard, because minute traces
of copper lower product stability.

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Meat Products

30.15

Lard has the following properties:
kg/m3

Specific gravity at

Heat of solidification
Melting begins at –37 to –40°C.
Melting ends at 43 to 46°C.
Point of half fusion is around 4°C.

–20°C = 990
20°C = 930 kg/m3
70°C = 880 kg/m3
= 112 kJ/kg

Specific heat in solid state

–80°C = 1.18 kJ/(kg·K)
–40°C = 1.42 kJ/(kg·K)

Specific heat in liquid state

40°C = 2.09 kJ/(kg·K)
100°C = 2.18 kJ/(kg·K)

Licensed for single user. © 2010 ASHRAE, Inc.

In lard production, refrigeration is applied so that the final product has enough texture and a firm consistency. The finest possible
crystal structure is desired.
Calculations for chilling 500 kg of lard per hour are
Initial temperature:
Final temperature:
Heat of solidification:
Specific heat:

50°C
25°C
112 kJ/kg
2.09 kJ/(kg·K)

te – tf
46 – 25
Sf = 100 -------------- = 100 -------------------------- = 24.4%
te – tb
46 –  – 40 
where
Sf
te
tf
tb

=
=
=
=

percent solidification at final temperature
temperature at which melting ends
final temperature
temperature at which melting begins

Latent heat of solidification:
112(24.4/100) = 27.3 kJ/kg
Sensible heat removed:
2.09(50 – 25) = 52.2 kJ/kg
Total heat removed:
(27.3 + 52.2)500/3600 = 11.0 kW of refrigeration
Assuming a 15% loss because of radiation, for example, in the
process, the required refrigeration to chill 500 kg of lard per hour is
1.15  11.0 = 12.7 kW.
Filtered lard at 50°C can be chilled and plasticized in compact
internal swept-surface chilling units, which use either ammonia
or halogenated hydrocarbons. A refrigerating capacity of about
23 W per kilogram of lard handled per hour for the product only
should be provided. Additional refrigeration for the requirements
of heat equivalent to the work done by the internal swept-surface
chilling equipment is needed.
When operating this type of equipment, it is essential to keep the
refrigerant free of oil and other impurities so that the heat transfer
surface does not form a film of oil to act as insulation and reduce the
unit’s capacity. Some installations have oil traps connected to the
liquid refrigerant leg on the floor below to provide an oil accumulation drainage space.
Safety requirements for this type of chilling equipment are described in ASHRAE Standard 15. Note that these units are pressure
vessels and, as such, require properly installed and maintained
safety valves.
The recommended storage temperature for packaged refined lard
is –1 to 1°C. The storage temperature required for prime steam lard

in metal containers is 5°C or below for up to a 6 month storage
period. Lard stored for a year or more should be kept at –20°C.

Blast and Storage Freezers
The standard method of sharp-freezing a product destined for
storage freezers is to freeze the product directly from the cutting
floor in a blast freezer until its internal temperature reaches the holding room temperature. The product is then transferred to holding or
storage freezers.
Product to be sharp-frozen may be bagged, wrapped, or boxed in
cartons. Individual loads are usually placed on pallets, dead skids, or
in wire basket containers. In general, the larger the ratio of surface
exposed to blast air to the volume of either the individual piece or the
product’s container, the greater the rate of freezing. Product loads
should be placed in a blast freezer to ensure that each load is well
exposed to the blast air and to minimize possible short-circuiting of
the airflow. Each layer on a load should be separated by 50 mm spacers to give the individual pieces as much exposure to the blast air as
possible.
The most popular types of blast equipment are self-contained airhandling or cooling units that consist of a fan, evaporator, and other
elements in one package. They are usually used in multiples and
placed in the blast freezer to provide optimum blast air coverage.
Unit fans should be capable of high air velocity and volumetric flow;
two air changes per minute is the accepted minimum.
The coils of the evaporator may have either a wet or a dry surface.
See Chapter 14 for information on defrosting.
Blast chill design temperatures vary throughout the industry.
Most designs are within –30 to –40°C. For low temperatures, booster
compressors that discharge through a desuperheater into the general
plant suction system are used.
Blast freezers require sufficient insulation and good vapor barriers. If possible, a blast freezer should be located so that temperature
differentials between it and adjacent areas are minimized, to
decrease insulation costs and refrigeration losses.
Blast freezer entrance doors should be power operated. Suitable
vestibules should also be provided as air locks to decrease infiltration of outside air.
Besides normal losses, heat calculations for a blast freezer
should include loads imposed by material handling equipment (e.g.,
electric trucks, skids, spacers) and packaging materials for the product. Some portion of any heat added under the floor to prevent frost
heaving must also be added to the room load.
Storage freezers are usually maintained at –18 to –26°C. If the
plant operates with several high and low suction pressures, the
evaporators can be tied to a suitable plant suction system. The evaporators can also be tied to a booster compressor system; if the
booster system is operated intermittently, provisions must be made
to switch to a suitable plant suction system when the booster system is down. Storage freezer coils can be defrosted by hot gas, electricity, or water. Emphasis should be placed on not defrosting too
quickly with hot gas (because of pipe expansion) and on providing
well-insulated, sloped, heat-traced drains and drain pans to prevent
freeze-ups.

Direct-Contact Meat Chilling
Continuous processes for smoked and cooked wieners use direct
sodium chloride brine tanks or deluge tunnels to chill the meat as
soon as it comes out of the cooker. Every day, the brine is prepared
fresh in 2 to 13% solutions, depending on chilling temperature and
salt content of the meat.
Cooling is usually done on sanitary stainless steel surface coolers, which are either refrigerated coils or plates in cabinets. Using
this type of unit allows coolant temperatures near the freezing point
without damaging the cooler; damage may occur when brine is confined in a tubular cooler. Brine quantities should be enough to fully
wet the surface cooler and fill the distribution troughs of the deluge.

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2010 ASHRAE Handbook—Refrigeration (SI)

Another type of continuous process uses a conveyor belt to move
wieners through the cooking and smoking process, and then drops
them into a brine tank. Pumped brine moves the product to the end
of the tank, where it is removed by hand and inserted into peeling
and packaging lines.

FROZEN MEAT PRODUCTS
Handling and selling consumer portions of frozen meats have
many potential advantages compared with merchandising fresh
meat. Preparation and packaging can be done at the packinghouse,
allowing economies of mass production, by-product savings, lower
transportation costs, and flexibility in meeting market demands. At
the retail level, frozen meat products reduce space and investment
requirements and labor costs.

Licensed for single user. © 2010 ASHRAE, Inc.

Freezing Quality of Meat
After an animal is slaughtered, physiological and biochemical
reactions continue in the muscle until the complex system supplying
energy for work has run down and the muscle goes into rigor. These
changes continue for up to 32 h postmortem in major beef muscles.
Hot boning with electrical stimulation renders meat tender on a continuous basis without conventional chilling. Freezing meat or cutting carcasses for freezing before these changes complete causes
cold- and thaw-shortening, which render meat tough. The best time
to freeze meat is either after rigor has passed or later, when natural
tenderization is more or less complete. Natural tenderization is
completed during 7 days of aging in most major beef muscles.
Where flavor is concerned, freezing as soon as tenderization is complete is desirable.
For frozen pork, the age of the meat before freezing is even more
critical than it is for beef. Pork loins aged 7 days before freezing
deteriorate more rapidly in frozen storage than loins aged 1 to 3
days. In tests, a difference could be detected between 1 and 3 day old
loins, favoring those only 1 day old. With frozen pork loin roasts
from carcasses chilled for 1 to 7 days, the flavor of lean and fat in the
roasts was progressively poorer with longer holding time after
slaughter.

Effect of Freezing on Quality
Freezing affects the quality (including color, tenderness, and
amount of drip) of meat.
Color. The color of frozen meat depends on the rate of freezing.
Tests in which prepackaged, steak-size cuts of beef were frozen by
immersion in liquid or exposure to an air blast at between –30 and
–40°C revealed that airblast freezing at –30°C produced a color
most similar to that of the unfrozen product. An initial meat temperature of 0°C was necessary for best results (Lentz 1971).
Flavor and Tenderness. Flavor does not appear to be affected
by freezing per se, but tenderness may be affected, depending on
the condition of the meat and the rate and end temperature of
freezing. Faster freezing to lower temperatures was found to
increase tenderness; however, consensus on this effect has not
been reached.
Drip. The rate of freezing generally affects the amount of drip,
and meat nutrients, such as vitamins, that are lost from cut surfaces
after thawing. Faster freezing tends to reduce the amount of drip,
although many other factors, such as the pH of meat, also have an
effect on drip.
Changes in Fat. Pork fat changes significantly in 112 days at
–21°C, whereas beef fat shows no change in 260 days at this temperature. At –30 and –35°C, no measurable change occurs in either
meat in one year.
The relationship of fat rancidity and oxidation flavor has not
been clearly established for frozen meat, and the usefulness of
antioxidants in reducing flavor changes during frozen storage is
doubtful.

Storage and Handling
Pork remains acceptable for a shorter storage period than beef,
lamb, and veal because of differences in fatty acid chain length and
saturation in the different species. Storage life is also related to storage temperature. Because animals within a species vary greatly in
nutritional and physiological backgrounds, their tissues differ in
susceptibility to change when stored. Because of differences between meat animals, packaging methods, and acceptability criteria,
a wide range of storage periods is reported for each type of meat (see
Table 7).
Lentz (1971) found that color and flavor of frozen beef change
perceptibly at storage temperatures down to –40°C in 1 to 90 days
(depending on temperature) for samples held in the dark. Changes
were much more rapid (1 to 7 days) for samples exposed to light.
Color changes were less pronounced after thawing than when
frozen.
Reports on the effect of different storage temperatures on fat
oxidation and palatability of frozen meats indicate that a temperature of –20°C or lower is desirable. Cuts of pork back fat held at
–6, –12, –18 and –23°C show increases in peroxide value; free
fatty acid is most pronounced at the two higher temperatures. For
storage of 48 weeks, –18°C or lower is essential to avoid fat
changes. Pork rib roasts of –18°C showed little or no flavor
change up to 8 months, whereas at –12°C, fat was in the early
stages of rancidity in 4 months. Ground beef and ground pork patties stored at –12, –18, and –23°C indicate that meats must be
stored at –18°C or lower to retain good quality for 5 to 8 months.
For longer storage, – 30°C is desirable.
The desirable flavor in pork loin roasts stored at –21 to –22°C,
with maximum fluctuations of 3 to 4 K, decreased slightly, apparently without significant difference between treatments. Fluctuations from –18 to –12°C did not harm quality.
Storage temperature is perhaps more critical with meat in frozen
meals because of the differing stability of the various individual
dishes included. Frozen meals show marked deterioration of most of
the foods after 3 months at –11 to –9°C.
Storage and Handling Practices. Surveys of practices in the
industry indicate why some product reaches the consumer in poor
condition. One unpublished survey indicated that 10% of frozen
foods may be at –14°C or higher in warehouses, –9°C or higher in
assembly rooms, –6°C or higher during delivery, and –8°C or
higher in display cases. All these temperatures should be maintained at –18°C for complete protection of the product.

Packaging
At the time of freezing, a package or packaging material serves
to hold the product and prevent it from losing moisture. Other functions of the wrapper or box become important as soon as the storage
period begins. Ideal packaging material in direct contact with meat
should have low moisture vapor transmission rate; low gas transmission rate; high wet strength; grease resistance; flexibility over a temperature range including subfreezing; freedom from odor, flavor,
and any toxic substance; easy handling and application characteristics adaptable to hand or machine use; and reasonable price. Individually or collectively, these properties are desired for good
appearance of the package, protection against handling, preventing
dehydration (which is unsightly and damages the product), and
keeping oxygen out of the package.
Desiccation through use of unsuitable packaging material is one
of the major problems with frozen foods. Another problem is that of
distorted or damaged containers caused either by lack of expansion
space for the product in freezing or by selection of low-strength box
material.
Whenever free space is present in a container of frozen food, ice
sublimes and condenses on the film or package. Temperature fluctuation increases the severity of frost deposition.

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SHIPPING DOCKS
A refrigerated shipping dock can eliminate the need for assembling orders on the nonrefrigerated dock or other area, or using a
more valuable storage space for this purpose. This is especially true
for freezer operations. Some businesses do not really need a refrigerated order assembly area. One example is a packing plant that
ships out whole carcasses or sides in bulk quantities and does not
need a large area in which to assemble orders. Many are constructed
without any dock at all, simply having the load-out doors lead
directly into the carcass-holding cooler, requiring increased refrigerating capacity around the shipping doors to prevent undue temperature rise in the coolers during shipping.
A refrigerated shipping dock can perform a second function of
reducing the refrigeration load, which is most important in the case
of freezers but serves almost as valuable a function with coolers.
Even with cooler operations, installation of a refrigerated dock
greatly reduces the load on the cooler’s refrigerating units and
ensures a more stable temperature within the cooler. At the same
time, it is possible to only provide refrigeration to maintain dock
temperatures on the order of 5 to 7°C, so that the refrigerating units
can be designed to operate with a wet coil. In this way, frost buildup on the units is avoided and the capacity of the units themselves
substantially increased, making it unnecessary to install as many or
as large units in this area.
For freezers, units should be designed and selected to maintain a
dock temperature slightly above freezing, usually about 1.5°C. With
this dock temperature, orders may be assembled and held before
shipment without the risk of defrosting the frozen product, and
workers can assemble orders in a much more comfortable space
than the freezer. The design temperature should be low enough that
the dew point of the dock atmosphere is below the product temperature. Condensation on product surfaces is one step in developing
off-condition product.
With a dock temperature of 1.5°C, the temperature difference
between the freezer itself and outdoor summer conditions is split
roughly in half. Because airflow through loading doors or other openings is proportional to the square root of the temperature difference,
this results in an approximate 30% reduction in airflow through the
doors (both those into the dock itself and those from the dock into the
freezer). At the same time, by cooling outdoor air to approximately
1.5°C, in most cases about 50% of the total heat in the outdoor air is
removed by the refrigerating units on the dock.
Because using a refrigerated dock reduces airflow through the
door into the freezer by approximately 30%, and 50% of the heat in
air that does pass through this door is removed, the net effect is to
reduce the infiltration load on units in the freezer itself by about
65%. This is not a net gain; because an equal number of these units
operate at a much higher temperature, the power required to remove
heat on the dock is substantially lower than it would be if heat were
allowed to enter the freezer.
The infiltration load from the shipping door, whether it opens directly into a cooler or freezer or into a refrigerated dock, is extremely
high. Even with well-maintained foam or inflatable door seals, a
great deal of warm air leaks through the doors whenever they are
open. This air infiltration may be calculated approximately by
V = CHW(H)0.5(t1 – t2)0.5

(2)

where
V = air volume, m3/s at higher-temperature condition
C = 0.017 = empirical constant selected to account for contraction of
airstream as it passes through door and for obstruction created by
truck parked at door with only nominal sealing
H = door height, m
W = door width, m
 = time door is open, decimal part of an hour

t1 = outdoor air temperature or air at higher temperature, °C
t2 = temperature of air in dock or cooler, °C

Time  is estimated, based on the time the door is assumed to be
obstructed or partially obstructed. If doors have good, wellmaintained seals that will tightly seal the average truck to the
building, this time is assumed as only the time necessary to spot
the truck at the door and complete the air seal.
The unit cooler providing refrigeration for the dock area should
be ceiling-suspended with a horizontal air discharge. Each unit
should be aimed toward the outer wall and above each of the truck
loading doors, if possible, so that cold air strikes the wall and is
deflected downward across the door. This downward airflow just
inside the door tends to oppose the natural airflow of entering warm
air, thus helping reduce the total amount of infiltration.
In general, a between-the-rails unit cooler has proved most successful for this purpose, because it distributes air over a fairly wide
area and at low outlet velocity. This airflow pattern does not create
severe drafts in the working area and is more acceptable to employees working in the refrigerated space. The preceding comments and
equation for determining air infiltration also apply to shipping doors
that open directly into storage or shipping coolers.

ENERGY CONSERVATION
Water, a utility previously considered free, frequently has the
most rapid rate increases. Coupled with high sewer rates, it is the
largest single-cost item in some plants. If fuel charges are added to
the hot-water portion of water usage, water is definitely the most
costly utility. Costs can be reduced by better dry cleanup, use of
heat exchangers, use of filters and/or settling basins to collect solids and greases, use of towers and/or evaporative condensers, not
using water for product transport, and an active conservation program.
Air is needed for combustion in steam generators, sewage aeration, air coolers or evaporative condensers, and blowing product
through lines. Used properly in conjunction with heat exchangers,
air can reduce other utility costs (fuel, sewage, water, and electricity). Nearly all plants need close monitoring of valves either leaking
through or left open in product conveying. Low-pressure blowers
are frequently used in place of high-pressure air, reducing initial
investment and operating costs of driving equipment.
Steam generation is a source of large savings through efficient
boiler operation (fuel and water sides). Reduced use of hot water
and sterilizer boxes, and proper use of equipment in plants with
electric and steam drives, should be promoted. Sizable reductions
can be made by scavenging heat from process-side steam and hot
water and by systematically checking steam traps. In some plants,
excess hot water and low-energy heat can be recovered using heat
exchangers and better heat balances.
Electrical energy needs can be reduced by
• Properly sizing, spacing, and selecting light fixtures and an
energy program of keeping lights off (lights comprise 25 to 33%
of an electric bill)
• Monitoring and controlling the demand portion of electricity use
• Checking and sizing motors to their actual loads for operation
within the more efficient ranges of their curves
• Adjusting the power factor to reduce initial costs in transformers,
switchgear, and wiring
• Lubricating properly to cut power demands
Although refrigeration is not a direct utility, it involves all or
some of the factors just mentioned. Energy use in refrigeration systems can be reduced by
• Operating with lower condenser and higher compressor suction
pressures
• Properly removing oil from the system
• Purging noncondensable gases from the system

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2010 ASHRAE Handbook—Refrigeration (SI)

• Adequately insulating floors, ceilings, walls, and hot and cold
lines
• Using energy exchangers on exhaust and air makeup
• Keeping doors closed to cut humidity or prevent an infusion of
warmer air
• Installing high-efficiency motors
• Maintaining compressors at peak efficiency
• Keeping condensers free of scale and dirt
• Using proper water treatment in the condensing system
• Operating with a microprocessor-based management system
Utility savings are also possible when use is considered with
product line flows and storage space. A strong energy conservation
program not only saves total energy but frequently results in greater
product yields and product quality improvements, and thus increased profits. Prerigor or hot processing of pork and beef products
greatly reduces the energy required for postmortem chilling. Removing waste fat and bone before chilling reduces the amount of
chilling space by 30 to 35% per beef carcass.

Licensed for single user. © 2010 ASHRAE, Inc.

REFERENCES
Acuff, G.R. 1991. Acid decontamination of beef carcasses for increased
shelf life and microbiological safety. Proceedings of the Meat Industry
Resources Conference, Chicago.
Allen, D.M., M.C. Hunt, A.L. Filho, R.J. Danler, and S.J. Goll. 1987. Effects
of spray chilling and carcass spacing on beef carcass cooler shrink and
grade factors. Journal of Animal Science 64:165.
Dickson, J.S. 1991. Control of Salmonella typhimurium, Listeria monocytogenes, and Escherichia coli O157:H7 on beef in a model spray chilling
system. Journal of Food Science 56:191.

Earle, R.L. Physical aspects of the freezing of cartoned meat. Bulletin 2,
Meat Industry Research Institute of New Zealand.
Greer, G.G. and B.D. Dilts. 1988. Bacteriology and retail case life of spraychilled pork. Canadian Institute of Food Science Technology Journal
21:295.
Hamby, P.L., J.W. Savell, G.R. Acuff, C. Vanderzant, and H.R. Cross. 1987.
Spray-chilling and carcass decontamination systems using lactic and
acetic acid. Meat Science 21:1.
Johnson, R.D., M.C. Hunt, D.M. Allen, C.L. Kastner, R.J. Danler, and C.C.
Schrock. 1988. Moisture uptake during washing and spray chilling of
Holstein and beef-type carcasses. Journal of Animal Science 66:2180.
Jones, S.M. and W.M. Robertson. 1989. The effects of spray-chilling carcasses on the shrinkage and quality of beef. Meat Science 24:177-188.
Kastner, C.L. 1981. Livestock and meat: Carcasses, primal and subprimals.
In CRC handbook of transportation and marketing in agriculture,
pp. 239-258. E.E. Finney, Jr., ed. CRC Press, Boca Raton, FL.
Lentz, C.P. 1971. Effect of light and temperature on color and flavor of prepackaged frozen beef. Canadian Institute of Food Technology Journal
4:166.
Marriott, N.G. 1994. Principles of food sanitation, 3rd ed. Chapman & Hall,
New York.
Thatcher, F.S. and D.S.Clark. 1968. Microorganisms in foods: Their significance and methods of enumeration. University of Toronto Press.
USDA-FSIS. U.S. inspected meats and poultry packing plants—A guide to
construction and layout. Agriculture Handbook 570. U.S. Department of
Agriculture.

BIBLIOGRAPHY
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